Making Buildings Stronger (Image 2)

Making Buildings Stronger (Image 2) Following the Feb. 7, 2003, car-bomb attack at the, cars continued to burn in the garage. While the devastation from a powerful 600-pound car bomb is obvious, the damage could have been far worse. Because engineers had designed the building to withstand the shaking of earthquakes, the structure was able to absorb much of the explosive force and did not collapse. When the blast struck, 750 people were in the building. However, because the building remained standing, more than 500 people survived unscathed and only 38 lost their lives. [One of four related images. See Next Image.] More about this Image El Nogal, composed of the 12-story structure and an adjacent, smaller four-story structure, was designed to withstand seismic shaking. Julio Ramirez and Mete Sozen of Purdue University, Luis GarcÃ­a of Universidad de Los Andes, Colombia, and Santiago Pujol of WJE Associates studied El Nogal to determine how a modern building designed to sustain earthquakes responds to an explosive blast. The researchers compared the Colombia event in February 2003 to a comparable event in Oklahoma City in April 1995, when the Murrah Federal Building (which was not designed for earthquakes) was eviscerated by an enormous truck bomb placed there by Timothy McVeigh. For engineers, similar concerns apply to both earthquakes and explosions, and engineers intend to use seismic design concepts to produce structures that address both threats. Specifically, the structures must be redundant (able to retain integrity after a component fails) and tough (able to retain integrity through cycles of stress). Researchers found that reinforcing details, which were integrated into the structure of El Nogal and were required by Colombia's seismic code were critical in preventing total collapse of the building. Such details helped minimize a tragedy not foreseen by engineers who designed the structure to withstand only the forces of an earthquake. The study was supported by National Science Foundation grant CMS 03-27753, awarded to Julio Ramirez.